Aftosa
by LittleLongHairedOutlaw
Summary: The outbreak of an epidemic amongst cattle around San Pedro is not what it first appears, and there are many different factors lurking beneath the surface. As far as Sherlock Holmes, scientist and consulting detective, is concerned, it almost makes him wish for mundane cattle rustlers.
1. Prologue

He hangs his gunbelt on the wall beside his hat, then hangs his coat over it. Not that he's hiding weaponry, mind, but there's no other peg and he can't bear to leave the coat on the floor. His armour is too essential to him for that.

Only a simple murder tonight, unfortunately. Evidence plain as day to him, especially with the latest word in from the devastated range. Cowhands are such excellent sources of salient news, especially when carefully plied with whiskey and cards and far too much free time. And so, in little more than an hour the murderer was arrested, lying now on a mean bed in a jail cell. Nothing to do with rustlers this time, at least. That would have been even duller.

He sighs, throwing himself onto the sofa and stretching out along its length, steepling hands under chin in the prayer position and filing away the night's murder. The twinge in his shoulder reminds him that he's perhaps not quite as healed as he would like to think, but at least he's cleared for work and the whole business is almost wrapped up.

All going well, tomorrow he'll have the final evidence. It should prove to be a _very_ interesting day indeed.


	2. Seven Months Earlier

"Come upstairs." Irene's voice is low and sultry in his ear, the invitation as expected as it is unwanted, breath warm as it traces the shell of his ear.

Sherlock sighs and pretends to take a sip of his whiskey. "I'm working," he says softly, out of the corner of his mouth, eyes trained on the supposed dentist dealing cards at the faro table.

"So am I. So let's work together." She follows his line of sight, her hair just brushing his cheek, enough to make him smirk. "Which one?"

""Doctor" McQuaid. Dentist idea came from Holliday, but his fingers aren't callused, which they should be because he claims to be practicing. Plus, what dentist would not repair his own chipped incisor? Conclusion, he's a fraud."

"What does he want then?" She slides onto Sherlock's lap, arms around his neck, making herself comfortable. He presses a kiss to her forehead, lips trailing down to rest beside her ear.

"Contract killer. He was playing poker with John Masters not long before he died. Based on what Stamford found when she performed the autopsy, there were some commonalities with arsenic poisoning, but it all happened far too fast, plus it would have required a larger dose of arsenic than what could routinely be administered during the course of a faro game. Combined with the chemical stains on McQuaid's fingers, he has some knowledge of mixing compounds. Hence, he's the murderer and the only reason he's still in town is to avoid being implicated in the affair. If he'd run, it would be far too obvious."

Irene turns her head, nipping Sherlock's neck gently, teeth grazing the skin just so. "What do you want me to do?" Her breath ghosts just over his pulse point, making his hair stand just slightly on end.

"Distract him. An hour at least. I need to search his room at the hotel."

"You'd better come upstairs later."

He grins deviously at her, eyes crinkling at the corners and she feels her own lips twitch in response. "I'll see what I can do," he murmurs, pressing his lips to hers for the benefit of surreptitious bystanders.

She kisses him back briefly before standing up, smoothing down the fresh creases in her dress, and sauntering over to the faro table, her dark hair flowing onto the red fabric creating the illusion of attractive danger. Instead of waiting to watch her turn on the charm, Sherlock knocks back his whisky, runs his fingers through his curls and puts on his hat. Nodding to Joe behind the bar on the way, he passes through the swinging doors as Irene gets to work on the "dentist."

The town is quiet, midday heat having driven most people indoors as it so often does. Sherlock flips his collar to shield his neck from the glaring sun, and hooks his thumbs into his belt loops, eyes on the ground so as to be less conspicuous. Wandering down a side street, he slips around the back of the hotel and in through the other door.

At this time of day, the majority of ladies are congregated in the lounge with their elegant and occasionally sneering conversation, while their men are in the bar or playing billiards or conducting whatever business has brought them to San Pedro as opposed to Tucson or even Tombstone. This leaves it clear for Sherlock to quietly go up the back stairs, find the right room and pick the lock, all in the space of three minutes.

The room itself is dark, curtains pulled shut even in the middle of the day. Though he isn't fully certain of what he is looking for, the dentist's bag seems a good place to begin. A search shows up nothing of interest except for a bottle of laudanum. Cursing softly to himself, Sherlock moves onto the chest of drawers which present only clothes and chemistry books with a couple of glass flasks. No sign of arsenic or cyanide or anything remotely toxic.

A glance at his watch shows that time is getting short, ticking down quickly and he needs to find _something_. McQuaid is clearly the murderer, so where are his poisons?

Unless he has them on him. Always a possibility. And why didn't it occur to him sooner?

His coat swirls as he turns towards the door, but McQuaid's trunk catches his eye again, specifically the bottom. The trunk was empty when he checked it, but something like that is always worth a second look.

The door loses its appeal, Sherlock instead throwing open the trunk lid. Empty, of course, as it had been before, but appearing five inches deeper on the outside than the inside.

False bottom.

Taking the small lever from his tool kit, he carefully prises open the decoy trunk floor, every moment aware of how little time is left. The bottom comes up easily, revealing its secret of a water canteen, mortar and pestle, and small, locked box. Fiddling with his lock pick, the box lid springs open. And there, nestled gently inside, is Sherlock's quarry. Clearly identifiable arsenic and hemlock, and what could very possibly be lead.

The grin that breaks across his face here in this dark room is a special, secret one reserved for these moments of breakthrough, for the rush of sweet satisfaction through his veins when the knowledge is his and his alone, before Lestrade and John get to hear his deductions. For a moment, he allows himself to savour this feeling of being right. Then the ticking clock comes back to him, so he carefully arranges the trunk as he found it and slips back out the way he came.

* * *

US Marshall Greg Lestrade is pleased to say the least when Sherlock swirls into his office all cheekbones and dramatic coat. The self-satisfied glint in his eye prompts Greg to stand up and put on his hat before even asking what breakthrough the detective has reached.

"Who am I arresting?" he simply asks, buckling his gunbelt and ensuring the pistol is loaded in case of trouble.

"The supposed dentist, Kenny McQuaid," Sherlock replies, sitting back on Greg's desk and taking off his broad-brimmed hat. The curls tumble free, unruly as ever. "He murdered John Masters with a poison comprised of arsenic, hemlock and what I suspect is lead. All of the evidence you need is under the false bottom in his trunk, and he is currently playing faro in the Comique."

Greg sighs, raising an eyebrow at Sherlock but deigning not to comment on the extent of his knowledge. Experience has taught him that when Sherlock Holmes makes a pronouncement on the location of crucial evidence, it's best not to know how he came to possess such knowledge. His lock-picking skills are proof enough. "Are you joining me then for the arrest?"

Sherlock smirks, but shakes his head. "No, but I'll wander over with you in that direction. Miss Adler demands my company."


	3. Aphthous Possibilities

"You really need to sleep more," Irene berates him, digging her fingers into his shoulders in an attempt to massage out the tension.

"You mean sleeping here, of course. In your bed instead of in the lodgings which I pay for." Sherlock's voice sounds bored, but Irene has known him long enough to hear the thread of amusement lingering beneath the surface.

"Sleeping at all would help you, no matter what you say about it slowing you down. That's why you're so tense now."

"I'm not tense."

"Yes you are." She kneads his muscles firmer as if to emphasis the point. "I suppose Lestrade has arrested the dentist."

"Yep. All neatly wrapped up with a bow. Ridiculously simple once I'd handed him the evidence."

"Does that mean you've eaten today?"

He grunts noncommittally, and really that is more than enough of an answer. Irene simply purses her lips and continues with the massage, refusing to get drawn into another argument with him over the same old story.

"Irene."

"Mhmm?"

"Thank you."

She smiles in spite of herself. "I know you're manipulating me, Mister Holmes, but it is nice to hear the words. John must be so pleased to see how your manners have improved."

"Now that you mention it, he has remarked on it. Though that was more to the effect that the world must be ending, truth be told. I meant to forget that." And for the life of him now, he can't remember why he chose to retain it. Perhaps just because it was John who came out with something so ridiculous and inane.

"And yet, you just couldn't bring yourself to. You're a closet sentimentalist, Sherlock. No point in denying it. The difficult façade can't fool everyone, you know."

* * *

When Sherlock eventually leaves Irene for the evening and goes back downstairs, he finds John waiting for him at the bar, nursing a glass of whisky. The scene is so unusual – John tends to favour beer, after all – that Sherlock takes a moment to deduce what has happened. But all that he can figure out is that it must be something to do with having been called out to the Marion Ranch in the morning.

John's hat is beside him on the bar, hair tangled from repeatedly running his fingers through it, an unusual nervous tic of his which rarely sees daylight and certainly not in public. His moustache seems to droop more than normal at the ends, and his boots are scuffed with dust, as is the bottom of his coat hanging on his chair. Clearly he's come straight from the ranch without going back to the house to clean up a bit. The knowledge of that is more than enough to set Sherlock on edge, though he refuses to show it. Enough that Irene is picking up on his sentiment.

"Lestrade said I'd find you here," John says by way of an opening when Sherlock pulls up a chair beside him. "He also said to tell you that McQuaid confessed to Masters' murder."

"And why aren't you polluting yourself with that ridiculous rubbish that you consider alcohol?" Sherlock asks by way of an answer, because of course McQuaid confessed after being arrested with such compelling evidence.

"I'd dare you to tell me that, but I know you won't be able to."

Sherlock looks at him as if disgusted, though secretly pleased at the challenge. "Marion's steer was more complicated than you'd thought, which is why you were held up out there all day and also why you came straight here. However, the whisky drinking is anomalous because normally after a long day you especially favour beer. So I suspect that it wasn't just an ill steer that got you hauled out there."

John watches to see that Joe is busy attending to someone else, and to ensure that there are no eavesdroppers, then leans in to whisper in Sherlock's ear. "I suspect it might be aphthous fever, but I need you to confirm it."

For once in his life, Sherlock is struck dumb, his Eastern education failing him, though of course he understands what his best friend has told him. The words to reply, however, simply refuse to come, milling instead in a confusing mess in his mind, half-forming questions before disappearing into the soup of thought again. John would be amused if the situation wasn't so serious.

"Aph . . . you mean to say that there's . . . are you sure?" In spite of his disbelief, he's disgusted at himself for stumbling over the familiar syllables.

John shakes his head. "Not quite. Unlike you I've never seen it before so I could be confusing the vesicles with a multitude of other things, but I'm almost positive that that's it. The fever, the lethargy, the blisters. They all fit, and his Mexican vaqueros have picked up on it too. Will you . . . will you go out there in the morning?"

The small seed of doubt isn't as comforting as it should be, but it's enough that he's able to feign only mild concern. "Suppose I should, just to be absolutely certain and out of scientific curiosity. Maybe it's something minor and boring."

"I've never heard you wish for something boring before."

Sherlock doesn't reply, caught in the barrage of memories flooding back at the mere mention of aphthous fever. The three years that he spent away destroying criminal networks from the inside, the days spent lining up infected cattle to be shot when he worked as a stockman to gather information on a slave-trading enterprise, the dark alley in New York where he was left for dead. The killing and violence that characterised those three years is never far away, but the thought that that dread-disease which played such a small but essential part in it might be in the Arizona territory plunges him back to those long, painful nights of watching his back and digging out information, while haunted by blood running from pistol holes in bovine foreheads.

Irene's right. He is tense, but not from the lack of sleep. And something tells him that he won't be sleeping on this night either.

John's hand on his arm jolts Sherlock back to the present, to the too-bright saloon and Irene leaning against the piano singing 'Red River Valley', all of the cowhands who don't realise what could possibly be stalking the range. And Sherlock doesn't want them to realise. For once, it would be delightful if everyone could remain in blissful ignorance.

"We'll have to wire Mycroft." John's voice is still low, an undertone belying the full potential horror of the situation. And though Sherlock is loath to admit it even now, Mycroft will have to know. Will have to make certain arrangements, though hopefully it won't get as far as it could. (And though he's never put much store by hope and faith, Sherlock almost wishes that there was logic behind such ideas. Logic he can work with.)

"Leave it until we know for sure. He'll have our hides if it's only some minor infection though I'll admit that that possibility is remarkably unlikely. They found it in Galveston only last week after all." Sherlock sighs and taps the bar to attract Joe's attention. "Cigar please, Joe. Think I might need one."

Joe glances toward Irene at the piano out of the side of his eye, but Sherlock notices it anyway and with all of the other thoughts swirling in his head is unable to bring himself to smirk. "Miss Adler says you can have as many as you want."

"My compliments to Miss Adler."

Joe wanders off to deal with a cowhand after leaning against the bar, and Sherlock lights up the cigar, revelling in the calming influence of the smoke. John refuses to comment, instead re-filling his glass, both of them finding relief from the newfound worry in their chosen pursuits, however long that relief may last.


	4. Blisters and Gunshots

**A/N: Not fully happy with this chapter if I'm honest, but it's not the worst either and perhaps it just needs me to step back and gain some perspective before it give it another edit. As it is it's fit for purpose.**

**Also, a warning that there are things referred to in this chapter which may be squicky to some (namely the slaughter of infected cattle), but I tried to keep as much as that out of it as possible. In fact, on that front I think I did well but forewarned is forearmed and I recommend you be on your guard because it is suggested.**

* * *

John knows that Sherlock did things which he wasn't proud of while he was away, knows he's haunted still by the memories of his actions and the actions of others. Knows that he's subtly different since he came back, calmer in some ways, better able to deal with people having worked so hard to blend into the background for so long, to escape the notice of those he was working to destroy. (And John's forgiven him for disappearing too, because how could he not?)

John also knows that there isn't any point in pressing Sherlock for information. He'll find out what he'll find out and it's better that way, because otherwise Sherlock will simply close up and hide his feelings even deeper than where they're at, leaving them to gnaw at him and plague his mind late at night without a case. That haunted look comes into his eyes far too often as it is.

So on this night of all nights when Sherlock reaches for the laudanum bottle, John doesn't berate him, simply nods and decides to check on him to be sure he hasn't too much again, ensure that it's just sleep and not unconsciousness. (Once was quite frankly enough to go through that worry.)

For his own part, John knows sleep won't be too easy tonight for him either. Every time he closes his eyes, he sees the blisters anew, the quiet acceptance on the faces of the vaqueros. Aphthous fever. Aftosa. Foot and mouth disease. All the one, just different names from different places, capturing one sinister meaning. John knows what happened back east too, in '80 and '84. Knows about the mass slaughter and destruction, the pits and cremations. Knows Sherlock and Irene played some part in the affair while on the run together. And knows, too, that though they were only cattle the killing touched something buried deep in Sherlock, something nobody could have known was there. So though John knows that the vesicles he's seen today can mean only one, he finds himself praying to a god he's not even sure he believes in that Sherlock says otherwise in the morning.

There's been enough shooting in their lives without adding more to it.

* * *

The morning is bright, blue sky bearing down on a dusty land with scarce water that yet manages to support a couple thousand cattle scattered across a vast range. A range where something simple has been preserved for years, horses and cattle and the men who work them from sun-up to sun-down and all through the night, guarding and watching, protecting against disaster.

(This is one disaster they can't protect against, no matter how many bullets in their guns or how much barbed wire they string.)

The thoughts of the insidious darkness lurking out there coupling with the lingering nausea from the laudanum destroy any appetite Sherlock may have had. The couple of mouthfuls of breakfast he swallows are more to keep Mrs Hudson from fussing over him than anything else. He and John leave before the sun is fully up, loaded with guns and ammunition, a prepared solution of carbolic acid, and the knowledge of what they will surely find.

The very land seems to know the death sentence hanging over it, seeming ghostly in the lightening day. There's not so much as a breath of wind through the dry prairie grass, no birds or jackrabbits or anybody else along the dusty road. Even the steers further in land, closer to the canyons and the shade, whatever scrub they can find though it's greener here than in other parts of the state. Everything is shrouded in a quiet hush as if waiting with bated breath for the world to wake up. (For gunfire and flying lead, perhaps.) Silent except for the horses' hooves on the gravelly dirt.

Both men are lost in their own thoughts and calculations, one locking away his emotions in a remote part of his mind, the other still praying to be wrong, both planning what will need to be done, already thinking ahead to the next phase of the operation. They're not veterinarians, not in the usual sense of the world. But as practical men of science, they know that if it's true then there's a lot of work to be done.

Al Marion himself, wiry thin and pale beneath his tan, is waiting for them when they reach the yard. Exchange nods in the place of words, before pointing their horses north, three riding abreast to where the herd has spent the night, kept close and together by a hastily-strung barbed wire fence. One steer is loose from the others, lying under the shade of a cottonwood tree, head in the dust, horns themselves seeming to droop. There is no need to question why, only one logical explanation.

Sherlock dismounts, pulling off his gloves and draping his jacket across his saddle, horse waiting without question at the reins on the ground in front of his feet. Positioning his hat to block the strengthening glare of the sun, he walks over to the steer whom fever and pain has lain so low that he doesn't get up. Marion and John join him after only a moment, with the rancher roping the steer around the horns, pulling his head back. That provokes the animal to fighting, but he's that weakened that it's largely ineffective, especially when John pulls on the rope too, stretching it taut.

First, Sherlock examines the hooves, notes the red rawness of the burst blisters behind and between the digits. The sight of them on all four feet, and the swollen coronets, causes his heart to sink in spite of his best attempts at numbness. Then he turns to the mouth with its semi-viscous ropy drool. That's enough in and of itself, and if this were a case for Lestrade he'd call it without going any further, taking into account the staring coat, visible ribs and sunken eyes. But it's not for Lestrade, and it brings back so many memories of Maine that he grabs the steer by the jaw and wrestles his mouth open, eyes falling immediately to the peeling tongue before passing to the ulcerated gums.

At the nausea rising in his stomach and the ringing in his ears, Sherlock lets his hands fall away. He closes his eyes for a moment, fighting to calm himself before reminding himself that this is Arizona and he's not destroying Moriarty's network anymore. It's a case. Just a case.

"What is it, Mister Holmes?" Marion's voice betrays nothing of the worry he surely feels and it is enough to pull Sherlock back to the present.

"Foot and mouth, Mister Marion. Also known as aftosa or aphthous fever." He surprises himself at how unconcerned he manages to sound, as if there isn't a tumult of memories waiting to come to the fore again. "We'll have to shoot him and burn the carcass. I'll wire Prescott when I get back to town and it's likely that the DA will want to destroy all livestock who've been in contact with him regardless of whether they show signs of infection or not."

"What'll we do until you get an answer from Prescott?" Marion loosens the rope from the steer's horns and lifts it away, drawing his pistol.

"Shoot anything showing signs of infection and observe the others. Do you have any cattle that haven't been in contact with these?"

"About a hundred head to the north and two hundred to the east."

Sherlock nods, washing his hands in the phenol solution and pulling his gloves back on, eyes averted as the pistol shot rings across the land. (No point in adding too many new memories to the old ones.) "I'll check them for signs now. Might be a chance that they're in the clear and maybe you'll be able to hold them."

* * *

The evening is closing in when Sherlock and John get back to town, sun sinking towards the horizon, bathing the land in a gold that brings out the dryness of the plains, Redbeard's deep red coat glowing like fire beneath the saddle. Lead, buckshot, gunfire fill Sherlock's mind though he tries to fight them back, tries to tune them out and absorb himself in something as mundane as the landscape, the lengthening shadows and night birds appearing, the mysteries that lurk in such a harsh, beautiful. (And beauty is a social construct, but it's a distraction, something fresh to ponder on and tease out, instead of blood streaking over a white face from a neat hole between hollow, empty eyes.) It's almost possible to believe that there isn't a cloud of thick smoke hanging over the range behind them, from one fire burning the carcasses of fifty. (He's never been a praying man – it goes against his scientific nature – but he thanks God anyway that the herds to the north and east are clear.)

The town when they return is loud, raucous. Saloons overflowing with the miners having come in, music thrumming out of the dance halls. It's the picture of debauchery and sin, but oddly comforting in its normality, untouched by the nightmare of blisters and gunshots. John takes the horses back to the livery, leaving Sherlock free to go to the post office.

It takes him a minute longer than it should to dictate the telegram, phrasing it in such a way that Mycroft won't think he's worried, merely doing his duty of reporting what needs to be reported. (Mycroft will know anyway, because Mycroft always knows. No use in giving him extra fodder though.)

The message sent, Sherlock reaches into his pocket and pulls out the twenty cents for the telegram. "Two dollars," he says, "if you'll wait here until a reply comes through. It might take a while."

The telegraphist grins. "No problem, Mister Holmes."

"I'll be in the Comique all night." With that, Sherlock turns on his heel and leaves, spurs rattling on the hardwood floor.

The Comique is louder than any of the other saloons likely are, the young women in Irene's employ prancing around, plying their trade with the gamblers and miners and louts in for the night. The piano music is lively, air laden with cigar smoke, whisky and sweat. Just a normal night in a normal saloon.

Pushing his way into the bar, Sherlock signals Joe for a bottle and a cigar.

"Bad day, huh?" Irene is beside him in a moment, arm sliding around his waist while she strikes the match and lights his cigar.

"Remember Maine in '84?" His words are soft, spoken as a whisper into her ear, but they have the desired effect. She pales and pulls back, looking at him with eyes wide and concerned, dropping her whore persona that's become like a second skin.

"Undercover unravelling the slave-trading enterprise? Somehow I don't think you're referring to that particular part of the affair."

"Excellent deduction." He knocks back a shot of whisky, feeling it bite his throat on the way down before filling another glass. "Fifty head gone up in smoke at the Marion ranch today."

"You don't mean –"

"I do."

She takes the glass off him, drinking it down in one mouthful. "Never thought we'd see it out here."

"Never thought we'd see it again, if I'm honest. I've wired Mycroft."

"Do you think he'll come down?"

Sherlock shrugs, knocking back another glass. "Who knows? You should probably be careful though."

"I'm always careful, Sherlock."

He chuckles in spite of himself and she smiles, but they're interrupted by the telegraphist running in and passing over Mycroft's reply. Sherlock reads through, eyes scanning the broken senses that come with telegraphy and pulling forth precisely what his brother means, before turning it over, writing a reply and handing it back to the young man.

"Another dollar for the reply to that one," he says over the noise of the crowd. The temptation to turn over the information in his mind is there, to break it into different parts, separate it out like a chemical solution before putting it back together. But now is not the time for that. He needs separate himself from the facts, to gain a different perspective first. As it is he's far too close to the outbreak (because it's not a case, not really, no matter the language used by Mycroft to convince him of that. It's an outbreak, possibly an epidemic, so everything needs to percolate differently, needs a different filter. And here, in this saloon, he has that different filter.

Just unfortunate that it's a whisky bottle.)


	5. Almost Epidemic

It possesses his mind, all that he can think of in the early hours of the morning. It got to Portland on a ship from Liverpool, but how could it get to Arizona? No ports trading with the outside world, and if it had been brought in from Galveston then how come it hadn't shown up anywhere else along the way despite passing through cattle country? How could there be two isolated cases so far apart? Unless they weren't connected, which still leaves the question of how it got to Arizona.

Pity there's not enough light to investigate by, because there must be something out on the range to give him a clue.

The whisky has long-since left his system, and the room is filled with cigar smoke, floor littered with smoked butts. John has locked away any drugs that he has, and though he knows that he could find some if he looked hard enough, Sherlock can't seem to muster the energy to try. Not now. He's opened a new file in his mental cabinet, placed everything he knows about the case in its pages - the age of the blisters, how many were infected, where they'd been in the days before the blisters showed.

None of the pieces fit together. Oh, the basic facts follow each other as far as the course of the disease is concerned, but there's no logical explanation and that's what makes his head spin in circles. (Unless, it was spread intentionally. But why spread it intentionally, and how? What purpose would it serve?) Perhaps it's too soon to make conjectures about this just yet. It's a mistake to theorize without all of the relevant information, and he knows that but he just can't help it. (He's never known his self-control to be so shot. At least, not without the influence of something else. And never has a night felt so long before. Not even those nights on the run with Irene.)

* * *

By the time that midday rolls around, Sherlock is at the far end of the Double Diamond, a long, long way from the Marion Ranch. (Yet, in truth, there's little difference between the two. Both hot and dry and dusty and cattle marked by blisters.)

"What next?" the rancher, Robards, asks, voice hiding emotion at the sight of the bloody carcasses, only the already infected lying stiffening beneath the noontime sun, the rest still waiting, verdict unknown.

"There's a steam shovel coming from Prescott and a cavalry unit from the Fort to handle the clean-up," Sherlock says, voice emotionless but not cold, feelings under control. (For now, at least.) "If any more show up, they'll take the herd. That was the only compromise I could negotiate." Silence. No gathering buzzards just yet but it's only a matter of time. "Mister Robards, have any of your stock recently come from Galveston? Or could they have associated with Marion's cattle in the last three weeks?"

He knows the answer, can read it plain as day in the rancher before him, the concerned, confused creases around his eyes and the nervous way he fingers his gunbelt. The bitten lip and haggard face.

"No. The last cattle I bought came in on the train from Amarillo and that was two months ago."

"Then you have no idea how this disease can have jumped fifteen miles? You have nothing that could be carrying it?"

Robards shakes his head, sunlight glinting off his greying beard. "No. Nothing."

* * *

By evening, there's a third case though at least this one is in Marion's northern herd. Whether that's a blessing or a curse remains to be seen, after all, if it were going to show up anywhere it'd be there first. So it's not quite enough to declare an epidemic. (But all it would take is one more man's stock to go down just the same. One set of blisters in an uninfected herd, then let the guns rattle.)

It's almost nightfall when Sherlock gets into town and stables Redbeard. There's no point in going to see Irene, or checking in with Lestrade, so he wires Mycroft with the latest situation and walks home through the dusty streets, hands buried in his pockets. For the first time in a long time, the itch burns deep in his chest to walk in the opposite direction and go to the opium den. To smoke until he forgets, until his mind is a blank, comforting canvas with none of this nonsense, no carmine and blisters infesting every thought, every memory.

How was he to have known, back in Maine, that it would haunt him like this? Breaking down Moriarty's network was never meant to hurt so much. It was to be a long, fantastic puzzle with a multitude of pieces coalescing, and full of excitement. It wasn't supposed to give him memories that stuck with him, with images of horrifying, bloody death. Who would have thought that he, Sherlock Holmes, of all people could be so affected by the slaughter of animals, ill though they may be? No murdered corpse ever left the profoundly wrong feeling that watching blood leak from between two trusting eyes did. Never caused the same feeling of dread at the sight of a blister, the apprehension at riding off with Redbeard in the morning, not knowing what he'd find, how many he'd watch being killed, crumpling to the ground, limbs twitching and kicking in a nervous response as life slipped away. They're only animals. So why is the whole affair so sickening?

(It is not the disease which he fears, the disease is science, perfectly understandable with sufficient time and equipment. It is the cure which affects him like this. The cure that isn't a cure.)


	6. Percolating the Theory

The map takes up most of the study wall, pinned carefully to the softwood board so that it doesn't crease. In crimson ink Sherlock has highlighted each of the infected premises, drawing around the ranch borders, totalling four places now. Within the red borders, he's used green ink to mark off ranch sections so far free of the disease.

The picture is not an appealing one.

It's been two whole days since the infection showed up on the Double Diamond, proving that it wasn't simply confined to the Marion Ranch. In one day alone it showed in three sections of range – Marion's third herd, the Bar Seventeen and the Tri-circle T. Sherlock tries not to think of the rapidity of the spread, the only logical explanation for which would be the movement of cattle. But he's looked at the records, and no cattle movements have taken place recently enough for that to be a factor.

Two ranches in the area remain uninfected, and these are bordered by where the infection has already hit. True, Henry Way's Box H is clear on one side, bordering a road in the next county and perhaps the stock are simply too far away from the Bar Seventeen. Yet Frank Canton's Flying W, which is surrounded by the contagion, has also remained free of it. It just doesn't add up.

Sherlock smokes another cigar – his third of the morning – as he pins a sheet of figures beside the map, then steps back to take in the scene again. Across the top of the wall he's pinned a timeline, charting the spread over the handful of days that it's known. Yesterday, the cavalry arrived and began mass slaughter on the affected ranches, no discrimination in whether individual animals have it or not. Wanton destruction of livestock, government sanctioned. A story repeated time and again, only this time far away from the coast.

If Sherlock lets his mind slip for a second, he can hear their guns and the rattle of the steam shovel Mycroft sent in. So he keeps his eyes fixed to the wall, to the map and the timeline and the figures, in the hope of finding a solution before there isn't a steer left on the range.

(At the rate this is spreading, that's going to be sooner rather than later. But at least the barbed wire fences have slowed it down a bit.)

The crook his elbow itches, and he scratches it absentmindedly. In Maine he caved and bought a supply of morphine when the slaughter was through, to block the images from his mind. (The smell seemed to linger somehow, just the same. Blood and cattle hide and straw and water. Something indefinable, really, bringing it all back to him.) Now, his skin seems to beg for the same sort of relief, the slide of the hypodermic and rush of drugs through his veins. (It may not be good for working, but it makes forgetting so much easier.) Only this time John is here, and has long-since taken his morphine away.

"Mrs Hudson has lunch made." John's voice pulls Sherlock out of his thoughts, as if he senses which direction his thoughts have turned. "She'd like it if you came out and had some. You need a break from this."

"John -"

"No. I'm not listening to it this time, Sherlock. You haven't eaten in three days or properly slept in five. And there's no use in saying that it helps you think to do this to yourself, because you need rest and you need fuel otherwise you won't solve this case. So you're going to come out and eat and then to go to bed for a few hours."

Sherlock twists his lips into a moue of distaste, knowing from John's tone that he's serious about it. "Only an hour though, alright?"

John's lips twitch as he forces himself to hide a smile. "Sure. An hour in bed after you eat. I'll get you if there's any news."

Sherlock nods and stands, a wave of dizziness forcing him to grab the edge of the desk to balance himself. Out of the corner of his eye he sees John frown, and instantly regrets getting up so fast if it'll only bring John's concerns down on him. If John thinks he's wearing himself out too much, it'll be even longer before he gets back to the case.

"How do you feel?"

"I'm fine. You're right. I just need a break from this." He gestures at the wall with all of its sheets of information.

"Here. Let me help before you hit the floor and give yourself a concussion." John takes his arm and puts it around his shoulders, wrapping his own arm around the thin waist of the detective for support. "Sleep first, then eat. It'll refresh you."

"Are you saving your lecture for afterwards?"

"You can bet on it."

Sherlock smirks ruefully. "Good to know."

Not for the first time, John praises his luck that Sherlock has a ground floor bedroom. Manoeuvring him upstairs when exhausted would be a nightmare, especially with his refusal to accept any sort of help and denial of his weakness. He sags in the doorway, all resistance draining out of his limp form, and John has to adjust his grip so that he doesn't just slide to the floor. It takes some managing, but he half-carries, half-drags Sherlock across the room and lays him down on the bed, head propped up on the pillows, face so pale he almost looks like a ghost with the dark shadows under his eyes. John tugs off his boots and pulls the covers up to his chin, fingers lingering long enough at his throat to feel reassuring pulse. (Every time this happens, John swears it'll be the last time and it never his. But he can at least ensure that the exhaustion is the only problem.)

Sherlock groans, blinking sluggishly as he comes to again. John fills a glass of water out of the pitcher on the nightstand and puts it to his lips, checking his pupils as he drinks.

"You're definitely staying in bed now," the doctor berates him, kindly but firmly. "I'll decide when you can go back to the case and it won't be a moment sooner."

Sherlock grumbles something incomprehensible - but which almost certainly contains the terms _idiot_ and _boring_ - and his eyes slip closed as he sinks into the bed. John shakes his head and pulls the curtains, eyes averted away from the haze of smoke just visible in the distance, a constant reminder of what still needs to be done.

* * *

It's dusk by the time that Sherlock wakes, a swirl of ideas and theories in his mind, the gift that resting has given him. (Once again, John conducts light, even if not in the most obvious of ways.) Visualising the map from his office, Sherlock studies the terrain, the distance between infectious zones, the possible sources of spread. Animal to animal transmission can safely be ruled out, which leaves indirect methods. If it had gotten into the water, then Marion would likely have been one of the last to go down, instead of the first, considering the direction in which the river flows. Even more unlikely is transmission by other animals, though it remains a very slim possibility. With the distance involved and the locations of which ranches went down when, air spread is also unlikely. And once the impossible has been eliminated, whatever remains, however improbable must be true.

Sherlock opens his eyes, a wave of nausea washing over him which he forces back before swinging out of bed. His boots are beside him and he pulls them on roughly, brushing back his curls with his fingers. If he's right, then the work has only begun.


	7. Bullet Through the Darkness

The evening has closed in across the land, as it is wont to do. Off to the side in the distance traces of purple remain in the sky, the sun having just slinked away, draining the light blue of the day and bloody red of the sunset with it. Redbeard raises dust as he trots along, though not so much as to warrant Sherlock to pull his bandana over his nose and mouth. Above them the first faint stars are quietly appearing. Any other time, it would seem like a completely ordinary night fall. But the whole range is quiet.

The range is not only quiet, but is eerily so, though some would favour the term obscene. Even the distant rattle of gunfire has disappeared, to return at sunrise. The almost silence is to be expected - after all, only three ranches still have livestock, and two of those have been condemned. The cavalry have given efficiency a whole new meaning, going so far as to bring in a second unit of cavalry men - equipped with shovels in order to keep up with demand, shooting coyotes so they can't help in the spread in their travelling across country in search of meat. (He never realised before how comforting he finds something so ordinary as the usual sounds of the country, lost now for however long this curse may last.)

Sherlock's fingers itch for his violin to drive the events of the last days out of his mind, screeching notes reaching into the darkness like a message sent into the abyss. An easy way to burn the numbness out of his chest, to settle his mind. (There was a time when numbness was desirable, but that was Before, before everything changed in such definitive ways. Before John looked at him with barely-hidden worry in his eyes. When there was still a network to take apart.) Of course, such a means of escape is not exactly possible right now, thoughts and questions, voices in their own right, left to circle through his brain, wondering, extrapolating, tormenting. Mentally redrawing the lines on the map in his study.

_Steered into the kitchen. Bowl of soup placed in front of him. The silent command to drink it, after all, he had agreed to this. All to get back to the case, to find the cause. The cause which he's almost certain he's ascertained, though it still seems too unlikely. The impossible, made improbable, made likely truth. More soup. And all the while a plan falling together to act on in the morning. A ride across country, ostensibly to inspect livestock and draw blood samples for experimental purposes, though of course those will play a part. Primarily in search of supportive evidence._

_A knock to the door. John's frown, and a muttered, "who could that be?" Sinking sensation in the pit of Sherlock's stomach, sense of foreboding. He swallows the soup, wipes his mouth, and follows John to the door. In front of them stands a cowhand, stubbled chin, wild eyes, twisting his hat in his hands._

_"__The woman in the saloon said that I could find Sherlock Holmes here." His voice is uncertain, concern lingering below the surface, clamped down on in the stoic way of the cowhand, too used to death, disappointment and pain with the harsh life of the range._

_Sherlock nods. "Henry Way or Frank Canton?" Straight to the point, as always. No need for formalities now, when the reason for this visit is all too obvious. Major news like aftosa spreads like prairie fire, albeit almost more unwanted. There's more to be salvaged after a fire. "It's Way, isn't it? The Box H? They've got one."_

_The cowhand's jaw drops, shock evident in his face, breaking through the badly-formed façade. "How did you –"_

_"__It's my job. I suppose he'd prefer if I confirmed it as opposed to going straight to the cavalry. Always a chance it could be made in error, no matter how sure he might be with so many others gone down, and he'll be hoping on that chance no matter how unlikely it may be. Yes. Fine. I'll ride up there in the morning and see for myself. Thank you for bringing this to my attention. If you go back to the Comique Irene will be glad to entertain you for the night if you mention me." He swings the door shut, and leans on it, beads of sweat breaking out across his forehead._

_"__That was –" John's voice is reproachful, almost scolding._

_"__Abrupt. I know. Better than stringing him along until he had to force the words out himself and substantially less tedious. I'll head out first thing. Maybe swing by the Canton place before I come back."_

_"__I don't suppose there's any way I could stop you." It isn't a question. Both know there's no need for that._

_"__None at all."_

It's been less than twenty-four hours. And the Box H is gone now too. In spite of all of his best efforts, a wave of guilt crashes into Sherlock. He didn't infect those cattle, there was nothing else that he could do. And yet, he passed sentence. Pulled the trigger on some of them. As good as killed the rest too. (Is this the same guilt that everyone else feels in their mundane lives? How do they live with themselves? Or is it magnified for him, enhanced with the capacity of his brain, heightened with the magnitude of what he's had to order?)

It's too late to go back and change this last week, though he wishes that he could. Wishes that he and John were out of the territory when Marion found his first ones. Wishes that the infection could have run its usually mild course without being discovered. Wishes that none of this destruction had come to pass. Wishes that there was some other explanation possible. (He's never wished for anything before, deemed it too ordinary an act a long time ago. Maybe he's getting sentimental, in which case Mycroft won't be pleased. Or maybe it's left over from Maine. Or maybe he's just getting old. None of those possibilities seem realistic, and yet one of them must be. Because there's no doubt about it that he's wishing for impossible, illogical things. None of this is the cold, hard reason he's always held above all things.)

He knows that he should find a place to make camp and stop for the night. Knows that John would want him to, and in fact is under the impression that he will, but Sherlock can't bring himself to. Needs to keep moving, keep heading in the general direction of the Flying W. To assure himself that there are, at least, _some_ healthy cattle left on the range, even at the expense of likely going back to square one. If he stops, it'll be the afternoon before he gets there. Otherwise, he could reach it much earlier. He knows Redbeard is more than up to it.

The night marches on, Redbeard's trot slowing into a walk as he picks his way through the darkness, Sherlock of little help to him with his mind in a whir, turning over the known facts again and again. The moon has risen high, casting a silver glow on the canyons and rock that mark the land, as if it were all moulded in metal. There's a chill to the air, but it's almost imperceptible for Sherlock who simply draws his heavy coat tighter around himself, finding comfort in its familiar weight. The quiet has its own current, a charge that crackles like lightning. It doesn't even register in his subconscious, though he does note Redbeard's growing uneasiness, the way he attempts to take control away from his master, escape off the trail.

"Behave yourself, boy," Sherlock murmurs. "The sooner we get there, the sooner we can lay this ghost. No time for side trails and rambling." The horse snorts as if in answer, and distantly Sherlock feels his lips twitch. Instead of smiling properly, though, he adjusts his hat, pushing the brim back to keep his curls out of his eyes.

The bullet pierces his left shoulder before he hears the shot, like a crack renting the quiet of the night. Tingling numbness spreads along his arm, reins falling from his suddenly-limp fingers. No pain yet. (Thank God for small mercies, but he can't bring himself to believe in a god.) Redbeard snorts, head thrown back before he takes off, ignoring Sherlock, ignoring everything except for the adrenaline coursing through his own blood.

It takes all Sherlock can give to maintain his balance, to grab the reins with his functioning right hand and hold on, wrapping the leather around his wrist so as not to slip off. It sounded as if the shot came from somewhere behind him, but he can't go back, can only hope to get to town and John and the relief that it promises. (Hopes he can hold the pain off, and somehow control the bleeding, if Redbeard will only _slow down._)

But the town is a long way off, and even with the horse galloping as he is, he feels the blood seeping through his clothes.


	8. Preparatory to Surgery

Not for the first time this morning, John glances at his watch between patients. He knows Sherlock likely won't be back until evening, considering his plan to take blood from some of Canton's stock, but that doesn't remove the uneasiness which has taken up residence in the pit of his belly, an unshakeable sense of foreboding.

However, he hides this sense of worry from the people who've come to see him. Most of them have only minor problems - broken fingers from bar-room brawls, lacerations for stitching, a sprain or two to add colour to the whole affair. He wonders, briefly, how Mike is faring across town, dealing with any number of various illnesses. Then he banishes the thought to focus on another minor injury.

The door swings shut behind Deputy Anderson (lacerated arm courtesy of a drunk and disorderly miner) only to open again a moment later. Molly Stamford née Hooper steps in, her light blue dress practical, dispensing with the frills favoured by more fashionable women. John quirks an eyebrow at her as he washes Anderson's blood off his hands, and she takes the seat reserved for patients.

"Busy morning?" she asks, the query always genuine when it comes from her as opposed to an attempt to make conversation. (John realises that in his worry he's starting to think like Sherlock as regards the boring normality of the human race, so he shakes his head to clear it before replying. Sounding is like Sherlock is not necessarily the wisest of things to happen.)

"Not the worst. Thank God no one was shot this time." (Though a shooting would be a nice change, the Sherlock-like voice in his mind whispers.)

Molly chuckles, then blushes, her hand flying to her mouth in her embarrassment. "I know it's not supposed to be funny, I just-" She swallows, and John smiles reassuringly at her.

"Go on. I'm sure whatever brings you here will be a refreshing change from the morning." He buttons his cuffs as he slides back into his chair. "So. What can I do for you? Surely it's not something you can't tell Mike about."

He regrets his off-hand comment immediately when she blushes to the roots of her hair. "No. No! Nothing like that. At least, I don't think so. I was just wondering if Sherlock was in.

John sighs and shakes his head, another wave of worry washing into his stomach. "No. He went out to Way's place yesterday. A suspected case but he's likely confirmed it. Then he was going to ride over to the Flying W. Said something about blood samples and comparison under a new staining method. Odds are that he won't be back until sometime tonight or in the morning."

"Oh. I just . . . I had some lungs that I thought he might be interested in. They have early tuberculosis lesions, some really good ones, and I know he's been looking for some for a while for one of his monographs so I just thought. . . I'll preserve them for him, just in case he decides to take a look." She stands to leave, straightening the creases out of her dress in one of her nervous tics.

"Don't worry about it. I'll make sure to tell him when he comes back, just be careful with them, yeah? Wouldn't like to hear of you getting ill or something with all of your autopsies."

With a nod and slight smile, Molly leaves. John's eyes slide back to the clock on the wall. Nine o' clock in the morning. He knows there's no reason to worry, but it won't leave him. A new patient comes in. The morning continues.

* * *

The world feels separate from him, intangible, vague. His head is woozy, the land around him slipping in and out of focus in time with the throbbing of his shoulder, blood soaking through the makeshift bandages he'd managed to somehow block the hole with.

The sweat breaking out on his forehead and trickling into his eyes has nothing to do with the sun which has long-since risen. Mouth dry, fingers limply holding on to the reins, eyes only half-open, too tired to keep them open and too stubborn to give in to the exhaustion threatening to overwhelm him. Needs to hold on, needs to get home so John can stitch him back together. The sense of it filters through his brain, perfectly comprehensible but difficult to carry out when the pain is fading into the background and he's more tired than he's felt before.

John will kill him if he doesn't stay awake. (He's never been one for hyperbole but it's oddly effective now, galvanizing him into forcing his eyes open and sitting straighter in the saddle, wincing when that makes his shoulder protest more.)

The effort is too much, weakness creeping in to his muscles and bones. His head sinks forward, chin on his chest, and he's too tired to raise it, too tired to do anything except keep holding the reins.

And even that is almost more than he can bear.

* * *

There's really too much paperwork in this profession, far too many reports that need to be filled out in relation to each and every case, be it a murder in the street or someone who just happened to drop dead in the saloon. (Can't finish that report anyway until he hears what Mrs Stamford has to say.)

Ten in the morning. The heat is steadily rising, so much that Lestrade shucks his broadcloth jacket and stretches. No harm in taking a quick break from this pile of bureaucratic nonsense, and he could do with more cigars.

With that thought in mind, he runs a hand through his greying hair and puts on his hat. Having changed the sign on his office door, he wanders down to the mercantile, not for the first time amused at the quiet that settles over the town as the heat rises. With rain and some cooler weather due in a few weeks it won't be like this for too much longer, but Greg will take what respite he gets.

The sound of hooves draws his attention before he gets as far as the store. A horse is visible at the far side of town, walking slowly with his head bowed, and even at this distance he can see that the rider is slumped forward. Nothing about it feels quite right, and Greg glances towards the Comique where Anderson is idling, making eyes at a saloon girl. The Deputy looks up, eyes meeting the Marshall's before he, too, looks towards the edge of town. The change that comes over him is immediate, hand dropping to the pistol at his waist as he looks back at Greg.

Nods are exchanged, and both men advance towards the incoming horse, whose coat is coming up a burnished bronze in the sunlight now that he's nearer. Greg's heart sinks at the sight, and he murmurs a curse under his breath, turning back to Anderson and shaking his head.

"It's Sherlock, isn't it?" And something in Anderson's voice means it's not even question, more a disheartened statement of fact. "I thought he wasn't due back until morning."

"He wasn't." The back of Greg's neck itches, and as he scratches it Sherlock slides off Redbeard's back, body limp in the Arizona dust.

They're beside him in a moment, and without being told Anderson turns back and runs towards Mrs Hudson's boarding house to get John. Greg registers Sherlock's pale face, the closed eyes and pale lips and dark curls sticking to his forehead with sweat. His heavy coat is only half on, where he must have eased his wounded arm out of it to bind the bullet hole. A wave of nausea washes over Greg as he kneels beside Sherlock, the smell of blood reaching his nose making him want to retch. It's certainly not the first time he's seen a bullet hole and blood spilled, and he's seen bodies that smelled much worse. But it's Sherlock and he looks half-dead already and surely there's some way that he can be saved.

* * *

When Irene hears Sherlock's injured, she knows what to expect, remembers intimately their two and a half years on the run and the state that he was in by the end. Leaving Joe to hold the fort in the Comique, she takes a flask of brandy and runs into the street. It's easy to see where Sherlock is, Redbeard still standing by his side with both John and Lestrade tending to his bullet hole.

She's beside them in a moment, giving the brandy to John and taking Sherlock's hand in hers. (It's been so long since she last held on to his fingers like this, probably when he was still out of his head after they came back.) His eyes are closed, and he'd look almost asleep only for the paleness of his skin, the sweat beading his forehead, the blood soaking his clothes. She knows it looks bad for him, knows his breathing shouldn't sound that pained and laboured, but instead of letting the worry overwhelm her she swallows it back and strokes his curls away from his face, his hat having fallen to the ground when he passed out.

With Lestrade supporting Sherlock's head so he won't choke, John trickles the brandy slowly in through his parted lips, watching as he swallows it before trickling in more. A low groan escapes from Sherlock's throat, and his eyelids flutter, lashes brushing his cheekbones.

"Easy, Sherlock, easy," John murmurs. "It's alright. Just swallow a little more."

Sherlock squeezes Irene's hand, grip far too weak for her liking. "John," the word is a pained gasp, forced out between clenched teeth. "Go, John. Looking . . . for you."

"No they're not, Sherlock. It's alright. The danger has passed. We just need to get you home."

"Hurts, John." His eyes open at last, seeming to roll in his head before settling on John, their grey-blue hue glazed with the pain and the bloodloss. "M'tired."

"I know you are. I know. You can rest soon, and I promise it won't hurt, but we need to get you home first."

Sherlock nods, eyes falling closed for only a heartbeat. "All right."

With painstaking care, Lestrade and John manage to bring the detective to his feet, half-carrying, half-supporting him down the street, his head lolling forward onto his chest, body too weak and tired to keep it up. Irene runs ahead, her skirts hitched up out of her way, to ensure that the way is open into John's consulting room. Sherlock is unconscious again by the time that they lay him out on the table, body limp and muscles slack in spite of the clenched jaw and tightness around his eyes.

"Irene, there's a solution of carbolic acid on the middle shelf of the left hand cabinet. There's also a fresh scalpel blade on the drawer to your right. Could you pass them over?" John's directions lack any of the worry bubbling in his stomach, calm now in the face of battle as he draws a syringe of morphine. "Greg, there're needles and suture in the drawer to your left. Put them in the steel basin with the scalpel and pour in a quarter measure of the solution. Then check on Mrs Hudson and the water that I asked her to boil when I went out." As his instructions are being followed to the letter, John eases Sherlock's coat off the rest of the way, followed by his black jacket. Taking his left arm – mindful of the shoulder injury - he examines the delicate blue veins in the crook of Sherlock's elbow, the memory coming unbidden to mind of the last time he saw a puncture mark marring the now-smooth skin. Carefully applying pressure to cause one of the veins to become more accessible, he slides the needle home, injecting the morphine into Sherlock's bloodstream with practiced ease. The tension bleeds out of Sherlock's face, slipping away as the drug takes effect, and John allows himself a moment to feel relieved.

"Is there anything else that I can do?" Lestrade asks, worry etched deep into the lines of his face.

"I think I can manage here, with Irene's help. Go and wire Mycroft the news."

A frown from Lestrade, and Irene pales. "Do you think that's wise?"

John looks up at them, eyes dark with his own worry. "I think it's necessary."


End file.
